Unveiling the BB Soft Shackle

[jcapo]

Originally Posted by Stumble

I really want to know where they got that lime green dyneema from...

Gator-Jaw® Soft Shackles • Bubba Rope

The website says its Plasma rope. Plasma is made from spectra.

[Seaworthy Lass]

Originally Posted by jcapo

Gator-Jaw® Soft Shackles • Bubba Rope

The website says its Plasma rope. Plasma is made from spectra.

I've just checked it out . Thanks for the link.

Two shackles made using ¼" rope (6mm) are $42.99
$21.50 seems a reasonable price if you are buying rather than making them.

Plasma is produced by Jeyco, an Aussie company:

PLASMA Spectra Fibre Rope

[Seaworthy Lass]

After a fair bit of thought and playing with the BB soft shackles I have made, today I used up my last bit of Amsteel and modified the design slightly. I have omitted both "locks" at the ends of the central bury (which the Better shackle has) and decided on what looks to be a good proportion.

It is an absolutely beautiful shackle to handle. I give it 5* .

My thoughts comparing the BB soft shackle to the current favoured designs, the Better (which incorporates a Diamond stopper) and High Strength (which uses a Button stopper) soft shackles :

Advantages of the BB compared to the Better:
- Smooth Button stopper instead of a Diamond with tail remnants sticking out of the end (this makes handling much easier and aesthetics better).
- The elimination of two locks may make the load distribution better.
Drawbacks of the BB compared to the Better:
- You need to learn to tie the Button, although I have found ease of tying with practice is near identical to the Diamond
(Time taken is no longer)

Advantages of the BB compared to the High Strength:
- Central buried portion instead of two separate legs. This makes handling easier and gives a neater finish
Drawbacks of the BB compared to the High Strength:
- The central bury adds one more step
- The central bury adds complexity and will make load distribution slightly less good
- Not as strong unless possibly a minimum of '27x line-diameter' bury of the tails is used. This guess is based on Evans Starzinger's load tests on the High Strength shackle. It needs load testing to verify bury required.

Comments are welcome .

Full instructions will follow.

SWL

[Seaworthy Lass]

Here are instructions for making for a BB soft shackle and a rough guideline of measurements. It makes a generous sized shackle of about 60x line diameter, which is nice for handling in 5 & 6 mm line, the two most common thicknesses we are using. I also think that a longer shackle length like this helps with load distribution, which is beneficial. This is about the length I have been making Better soft shackles for general use.

You could shorten this if you wanted by shortening the amount of central bury and/or shortening the tail bury (I would not shorten the tail bury to any less than 10x line diameter, as it needs to tuck in neatly). Lengthen by lengthening the central buried portion. Strengthen it by increasing the bury of the tail to approximately 30x line diameter (estimate).

This has not been load tested (is anyone able to do this?), but I am guessing it should be at least the same strength as a Better soft shackle, if not a bit higher.

http://i1377.photobucket.com/albums/...psymymhlaw.jpg


INSTRUCTIONS FOR THE BB SOFT SHACKLE

Z = Amsteel Blue diameter (units don't matter, as long as you keep them uniform; working in mm is much easier than in inches)
Finished shackle length from tip loop to base Button = 60 Z

Approximate amounts of line needed if using 4-8mm Amsteel:
Very bare minimum (use only if you are skilled with the button) = 220 Z
Amount if you are reasonably comfortable with the button = 230-240 Z
Amount if inexperienced with the button = 250 Z

- Tape the ends of the line to stop them unravelling while you work.
- Find the halfway mark
- Measure 7 Z from this and squish the line together to open up the weave
- Using a marlin spike (I find a fid too sharp for this), poke a hole cleanly through it a little below this point leaving 6 strands on each side and making sure none of the strands are snagged. This hole is B.
- Poke the longer end of the line through B. A fid helps, but is not essential for this step.
- Insert 4 6-8 lines through the loop and tighten up the loop lightly around them
- Tape the two lines together near the loop to secure and remove the 4 lines. The tip of the loop is A.
- On the longer line mark 15 Z from A. This is C, the entry point of the fid
- Measure 35 Z from there. This is D, the exit point of the fid
- Insert the fid into the entry point of the longer line, with the shorter line fed into the fid, and feed it though to the exit point
- Pull through the line and milk the cover down firmly. Hold and tape securely so the cover does not slip back . The outer covering over the buried portion will enlarge and end up shortening the final buried length to about 33 Z
- Measure 15 Z from the exit point and tape the 2 lines together firmly with the edge of the tape at the 15 Z mark. This is E and where the base of the Button will sit.
- Mark the working ends at their tip so that they are the same length. This enables you to check if you are tightening the Button evenly
- Tie the button and snug up evenly and reasonably firmly. Step by step instructions for the Button are in posts 4-20 of this thread:
http://www.cruisersforum.com/forums/...ot-155591.html

Tighten up the Button:
- Using a Marlin spike and starting from one standing end at the base move anticlockwise and tighten as hard as you possibly can by pulling on the spike.
- Repeat with the other standing end and make sure the length matching marks on the two working ends indicate an equal length
- Remove all the tape
- Poke the loop and working ends through a suitable washer (13mm inner diameter with just hold 6mm line) and pop under the jaws of a vice, leaving the jaws a little loose so the line can move freely.
- Insert a rod into the loop and pull up as hard as you can on the two standing ends
- Wind a working end around a rod and pull as hard as you can
- Repeat with the other working end
- Repeat the last 3 steps

Bury the working ends:
- Each working end will be fed into the standing leg immediately clockwise to it when looking down on the head of the Button. This will tuck the end into its corresponding standing portion.
- Insert a marlin spike between the strands and into the core of one standing leg as close as possible to the base of the Button and create a clear opening by gently wriggling (try not to snag any fibres)
- Insert the fid with the correct line fed, feed the fid through the core and exit at the edge of the long buried portion and pull the line through
Milk the cover firmly and mark the end of the working line
- Pull on the working line to expose it again, cut it off at the mark and taper the end third evenly
- Milk the cover over it
- Repeat with the other working end

Pretension the shackle:
Evans Starzinger recommends applying load to a soft shackle and leaving it for about 20 minutes to pretension the stopper and improve strength.
I have no Dyneema left, but next year I am planning to makes two lengths up with eyesplices on each end, one eye just big enough to feed the loop of the soft shackle through and snug it up against the button. Two are required to make sure the load on the Button is symmetrical. Line can be connected to the loop of the shackle at one end and the two eyesplices at the other end and then tightened between two winches (one can be secured to a cleat/bollard if you have a sufficiently strong one).
Anyone with a better idea of how to pretension?

That's all folks .

SWL

[Pyxis156]

Awesome job furthering the development of the soft shackle and documenting it for the rest of us to use... hugely appreciated!


One quick question: The first step of Tighten Up the Button instructs "Using a marlinspike and starting..." Could you please elaborate a bit on this, I am not clear on exactly how you are using the marlinspike to tighten.


Thanks again!

[Seaworthy Lass]

Originally Posted by Pyxis156

Awesome job furthering the development of the soft shackle and documenting it for the rest of us to use... hugely appreciated!


One quick question: The first step of Tighten Up the Button instructs "Using a marlinspike and starting..." Could you please elaborate a bit on this, I am not clear on exactly how you are using the marlinspike to tighten.

Thanks again!

I am glad the instructions are useful .

Once you have tightened moderately with your fingers, it is hard to gain any purchase to tighten up the stopper really firmly. So I trace the line from the standing end (the taped bit) and when it first emerges I push the spike under it and pull. The first pull can't be too hard as it will pull the line out of the tape.

Then trace the line to where it emerges again, insert the spike under again and this time pull with all your strength. It needs a total of three insertions of the spike before the final tighten is done by pulling on the loose end that has emerged at the base.

Then repeat with the other bit of line.

You can really only do this once with the marlin spike if you have pulled as hard as you can on the first round.

It barely shifts at all in the vice after that and ends up like concrete.

[Seaworthy Lass]

This how the BB soft shackle detailed in post #49 looks closed.

Does anyone have access to equipment to check the strength of this design?

http://i1377.photobucket.com/albums/...psw0xro6dk.jpg

[jcapo]

The last time I tried this design I tried to tighten with a single piece of line with an eye in each end. Getting equal tension was difficult. I didn't try two lines.

Ascii art won't work here or I'd sketch something. Picture a piece of steel flat stock with a hole in the center for the shackle tails and a hole on either side of the center hole for a U-bolt. The noose goes through the center hole with the button on the U-bolt side. the pull is between the noose and the U-bolt.

A U-bolt really won't work at the loads we need to apply unless it is a very substantial U-bolt. A fabricated fixture made from at least 6mm stainless maybe.

I have transverse inboard chainplates. The aft lower has an extra hole that the tails fit through rather nicely. I can tension from the button to the noose with a cockpit winch. The button knot is tight but not as tight as I can get a diamond knot with the same pressure pulling tails to noose.

A large winch and a good anchor point is needed to really tighten the knot in this design.

[jcapo]

Originally Posted by Seaworthy Lass

Does anyone have access to equipment to check the strength of this design?

These folks will break it for $25.

TreeStuff - Splicing Break Test Service

There should be someplace similar in the EU.

[Seaworthy Lass]

Originally Posted by jcapo

The last time I tried this design I tried to tighten with a single piece of line with an eye in each end. Getting equal tension was difficult. I didn't try two lines.

Ascii art won't work here or I'd sketch something. Picture a piece of steel flat stock with a hole in the center for the shackle tails and a hole on either side of the center hole for a U-bolt. The noose goes through the center hole with the button on the U-bolt side. the pull is between the noose and the U-bolt.

A U-bolt really won't work at the loads we need to apply unless it is a very substantial U-bolt. A fabricated fixture made from at least 6mm stainless maybe.

I have transverse inboard chainplates. The aft lower has an extra hole that the tails fit through rather nicely. I can tension from the button to the noose with a cockpit winch. The button knot is tight but not as tight as I can get a diamond knot with the same pressure pulling tails to noose.

A large winch and a good anchor point is needed to really tighten the knot in this design.

Sounds like it would work for pretentioning, but yes, the metal and U bolt would need to be strong. I imagine this is what you have in mind with a hole just big enough to feed it through?



If it works with two Dyneema pieces with eyesplices it is something cruisers could do easily on board. I will test it out next year.

Originally Posted by jcapo

These folks will break it for $25.

TreeStuff - Splicing Break Test Service

There should be someplace similar in the EU.

For results to be statistically significant, it may need 10 pulls or more depending on the spread. A few different lengths of tail bury would also be useful. It quickly adds up!
I am confident enough with the strength being at least as good as the Better, to personally use the BB soft shackle. Data is always good though and may give others the confidence to try making them .

SWL

[jcapo]

Originally Posted by Seaworthy Lass

Sounds like it would work for pretentioning, but yes, the metal and U bolt would need to be strong. I imagine this is what you have in mind with a hole just big enough to feed it through?

Yes, that's what I was trying to describe.

[estarzinger]

I guess I am puzzled by the need for anything special to tighten the stoppers.

On the boat, I do it between my two primary genoa winches. I put a line on one winch (either just wrapped in the normal way or with a tug boat hitch) and a bowline on the end (bowline is good because it can be broken open even after high loads - but you could use a line with a spliced loop also. On the other winch I put my 'puller line' - again either a bowline or spliced loop on the end. Then I connect the two bowlines/loops with the soft shackle. Then I crank on the winch, pretty much as hard as I can (for normal size dyneema) - let it sit and crank a bit more and let it sit.

The primary winches should certainly be mounted strong enough to take their max load/pull. and at least on my boat have a clear path to each other. So are fine for this job. But you can use any other strong point for the 'fixed end'.

AT least with my winches you can't get enough load with a 1:1 pull to break the normal soft shackles but it is enough to set the stopper quite well and your working load is unlikely to be higher than your max winch pull. You can make a 2:1 purchase if you want to try breaking them or setting them even more fully . . . . but #1 be very careful if/when they break and #2 the 2:1 turning point needs to be really strong - a normal yachting block will not do it. The easier thing is to pick up an auto body shop hydraulic ram for a couple $100, and then you can pull max loads to your hearts.content

It is nice to have a load cell in the pull so you have numbers and complete repeatability, but it is not necessary, just crank really hard - these things are very strong and you will not break them.

[seandepagnier]

I've been using soft shackles for years. I use for hanks on sails as well as attaching jib sheets to share then for all the sails.

[jcapo]

Originally Posted by estarzinger

I guess I am puzzled by the need for anything special to tighten the stoppers.

I have no trouble tightening a diamond knot pulling from the tails and the noose with a Lewmar 52 cockpit winch. Bend the tails together and you have a loop. The bend will set before the pre-tensioned diamond knot starts to give up its tails or the standing ends.

When I have tried using lines on the button knot it always resulted in one line abruptly slipping around the knot and all of the tension winding up on one side of the knot. I had no joy getting the tension equal and keeping the lines balanced on each side of the button.

Using the chainplate I mentioned above for the button knot anchor, I can pull about an inch of standing ends out of the button after tensioning the working ends with vise grips and a hole in 3/4" oak. The button knot is very hard and small but not as hard as I can get the diamond knot.

[estarzinger]

^^ - I 'close' the soft shackle - into a loop, using the soft shackles own noose - when putting the tension on - there is no slipping and it tightens up everything evenly - just as it would be in use.